Abstract We hypothesize that anger-induced perseverative cognition (or rumination) is a determinant of elevated blood pressure (BP) and such cognitions may be observed during post-anger recovery in the laboratory, and during ambulatory monitoring in the natural environment. Sustained BP elevation in turn confers independent risk for end organ damage (EOD). The main goal of the present research is to extend our understanding of the role angry perseverative cognition in sustained BP elevation by studying situational factors that influence the perseverative nature of these thoughts, in interaction with trait measures of rumination. Specifically, we will study the effects of a situational factor: an anger-recall provoking social encounter (via the Extended Type A Structured Interview; ESI) in interaction with trait tendencies to engage in perseverative angry cognitions, or rumination. We have found measures of this trait to be a useful predictor of behavioral rumination and poor BP recovery in the laboratory, and preliminary data indicate that persons who tend to engage in such cognitions tend to have higher ambulatory BP levels. We will use both a laboratory and an ambulatory BP monitoring component to study this type of cognition. A mixed design (1-between (level of trait rumination), 1- within (provocation or anger vs. neutral recall) is proposed. Participants with varying levels of trait rumination wear the ambulatory BP monitor during both a neutral and then again during an angerprovoking social interaction (one month apart, counterbalanced). During the laboratory portion of the session, which occurs early in the morning, we will assess BP continuously during pre-task, task, and post-task (15-minute recovery) periods; in addition, post-task cognitions will be assessed as well. Immediately following the recovery period, participants will wear an ambulatory BP monitor for the succeeding 24-hour period, and will complete an electronic diary, providing information concerning physical activity, mood, and cognitions. We hypothesize that we will observe (1) a main effect of the manipulation (anger-recall induction will produce greater post-task angry cognitions, poorer BP recovery assessed in the laboratory, and elevated ambulatory BP); (2) a main effect of the trait construct (persons who score high on trait rumination will tend to report more angry thoughts, and evidence higher ambulatory BP, than low trait ruminators); and (3) an interaction between these factors, such that participants who score higher on trait measures of rumination, and whose anger-recall is provoked, will evidence the highest frequency of angry cognition, the poorest BP recovery in the laboratory, and the highest ambulatory BP. Our long term aims are to understand one of the possible cognitive mechanisms that may be implicated in sustained BP elevations and eventual EOD.